Loft Boarding options

[jondunk]

Hi there,
I am planning to board out a section of my loft for light storage. The plan is to lay 100mm insulation between the joists and then lay the boarding over that. I have three question in regard the boarding which I would appreciate advice on:

1) should I use Knauf Space Board (52mm thick) laying two layers of the board followed by a layer of chipboard as the Space Insulations suggest or should I use the B&Q Insulated Timber Loft Board (123mm thick) which is an all-in-one insulation board complete with chip board top layer.

For the area I am covering the cost difference in negligible so im just keen to put the most efficient option down. Obviously the B&Q product will be easier to lay.

2) Are there any tips when screwing the chosen method down? Obviously something around 123mm thick will require a pretty long screw which may make hitting the joists a bit tricky?

3) Finally are there any condensation concerns I should be aware of when re-insulating the loft?

Many thanks, Jon

 

[mointainwalker]

Starting at the back.

3) You should put down a vapour barrier (plastic-sheet) over the whole ceiling - inc joists - so that warm moist air from the habitable space does not rise into the loft and condense.

Don't insulate under the water tank(s) if installed.

Don't cover any cables for major power consumers such as electric-shower, immersion heater with insulation as they may well overheat.

Not familiar with products you quote.

Why not use fibre-wool rolls ?

a) It is the best value pnds vs insulation properties by far
b) It is non-flammable unlike the board material

 

[jondunk]

Thanks for the advice.

I plan to use fiber roles for a large amount of the loft space, but will lay insulation boards & chip board in a 3x3m section for storage.

In terms of Electrical cables, There is only the cables required for ceiling lighting (simple ceiling roses) so it sounds like it is to lay the insulation over these cables?

ta